1. Field of the Invention
The present invention relates to a toilet bar suitable for cleansing. In particular, it relates to a toilet bar that has a specific formulation and plasticity or surface properties.
2. The Related Art
Toilet bars are well known for providing a wide range of skin care and cleansing benefits and are frequently made available to consumers in aesthetically pleasing shapes. Toilet bars that contain high levels of soap and synthetic surfactants are excellent for cleaning and usually have sufficient hardness to be economically extruded into a billet and stamped into a final attractive shape. Stamping, however, does not provide for creating intricate three dimensional shapes. Toilet bars that are transparent or translucent and/or contain high levels of components that are liquid at room temperature are usually too soft to be stamped and must usually be cast in a shaped mold or frame from a flowable feedstock. Casting also has limitations regarding the creation of intricate shapes. The cast bar will often have at least one flat surface upon hardening and will thus limit the choice of shape of the finished bar unless further process steps are employed to shape the flat surface(s). Additional steps will add to the complexity and cost of making such bars. Manufacturers have sought to provide to the consumer aesthetically pleasing shaped toilet bars that are shaped on their entire surface while attempting to meet a wide range of skin conditioning qualities, manufacturing and formulation constraints. A brief representation of the prior art is set forth below.
U.S. Pat. No. 3,856,449 issued to Fisher on Dec. 24, 1974 discloses a wire trimmer for trimming soap extrusions to obtain improved surface finish for soap. The cut lines will all be parallel to the direction of motion of the extruded soap.
U.S. Pat. No. 5,083,486 issued to Allison et al. on Jan. 28, 1992 discloses a method and apparatus for trimming non-soap solid stick deodorants to provide for a protruding rounded deodorant stick in the container.
U.S. Pat. No. 6,024,967 issued to Fattori et al. on Feb. 15, 2000 discloses a method and apparatus for shaping a top surface of a non-soap antiperspirant or deodorant product to have a compound-curved shape using a plurality of cutting blades.
It has been discovered that three-dimensional shaping via cutting can be usefully employed to produce aesthetically pleasing bar shapes for specifically formulated toilet bars that unexpectedly possess a defined range of plasticity in order to produce a bar with an acceptable appearance (i.e. having minimal or no visually detectable surface defects such as cracks and gouges). Such plasticity can be quantified by the fracture initiation energy (Gic) and the fracture energy parameter (Gc) from a three-point bending test described below. Moreover, a specific range of yield stress (σy) was also unexpectedly found to be an important property for preparing a bar with an acceptable appearance after cutting i.e. avoiding surface defects, as well as for generally efficient processing of the inventive bar. The inventive bar was discovered to have a distinctive striated topographic pattern compared to bars shaped by stamping or casting, and this striated pattern can be quantified using microscopic analysis techniques described below.